Sound recording and reproducing system



July 18, 1933.

W. HERRIOTT SOUND RECORDING AND REPRODUCING SYSTEM Filed April 24. 1931 INVENTOR m HERRIOTT ATTORNEY Patented .luly 18, 1933 llNl'lED STATES VJ'ILLIAEI Z-IERRIOTT, F FR-EEPORT, NEW

EATOR-IES, INCORPORATED, OF

SOUND RECORDING AND Iii-PRODUCING SYSTEM Application filed April 24-,

This invention relates to sound recording and reproducing apparatus and particularly to the positioning of a lamp filament forthe proje tion or" light to the sound record or sound record area of a film. v

A machine for recording sound on film provides means -for the propulsion of a film at 5. uniform velocity ast an intense and narrow heam or" modulated light. In many machines of i character a light source is employed cor ing of aribbon or coil filament lamp. A condensin lens system is used to collect a en amount of light from said source Wlnc t is focused upon a particular area of a An objective lens serves to pro: ell defined image of the aperture med by the lightvalve ribbons uponthe sound record area of the film.

o the photoelectric cell after passing the photographic sound record of the In many reproducers 01 this character source is employed consisting of a r coil filament lamp. A condensing ns system, a mechanical slit and an objecused to furnish an intense ght at the plane of the film. ht ser "es to scan the modulat- Other reproducers employ =1 source, an objective lens and a to the film. e recording or reproducing mas necessary to adjust the lamp filaconsiderable precision to obtain the -ient light for sound translation. A ber of different methods of adjusting hips to position the filament for maximum illumination at agiven area have been need. i. majority of the methods used at the present require that portions of the apparatus or the machine be disassembled for this adus inent. This disassembly is repeated upon ach replacement of the lamp.

The object of this invention is therefore to provide in a sound recording or reproduce ing machine, an indicator and cooperative means therefonto indicate When a lamp fila- 1931. Serial No. 532,535.

positioned to provide maximum light at a given area for most efficiently recording or reproducing sound.

One embodiment of this invention comprises an optical device, and screen for depicting the relation of the lamp filament posi tion to the optical axis of a lens system and the axis of an area to be illuminated. This device consists essentially of an objectivelens and a disc or screen provided with crossed lines. The objective lens and disc are so located as to produce on the disc or screen an enlarged real image of the lamp filament. The disc or screen may be made of glass and may have two lines engraved or etched upon a finely ground surface. These lines are located at right angles to each other and intersect the center of the disc. The glass disc may be placed on the side of the lamp opposite to that occupied by the optical system used for projecting'light to the film. cross line disc may be placed any convenient distance from the lamp filament. The objective lens is used for sharply focusing the image of the lamp filament upon the cross line disc. The equivalent focal length of this objective lens may be so chosen that it will project a sharp imao'e of the lampfilament upon the surface of the disc at a convenientmagnification, for example, a magnification of 4 tot; times. 7 7 1 V The screen may be variously formed and made of a variety of materials. For the sake of ease and uniformity of description this screen will be hereinafter termed a crossline disc. 7

It is not essential that the cross line disc and associated objective lens be at the opposite side of the lamp filament from the film. It is apparent that this cross line disc and associated objective lens may be set in tion atvarious angles and quirements set forth herein. I

The cross'line disc is not used in making theoriginal adjustments. The original adjustments must be made for either the recording or reproducing machines by the methods prescribed for each particular machine. /Vhen the lamp filament. has thus been positioned for maximum light efliciency the ment is accuratel osistill fulfill-the re- YORK, ASSIGNOR T0 BELL TELEPHONE LABO- NEW YQRK, N. Y., A CORPORATION'OF NEWYORK The objective lens, lying between the cross line disc and the lamp filament, is focused by sliding it longitudinally in its holder. This objective lens is moved to a position where an image of the lamp filament is sharply focused upon the ground surface of the cross line disc or screen.

. be held in a framework which is arranged for adjustment. This adjustment is made after the image of the lamp filament is sharply focused upon the cross line disc. The adjustment consists in moving the disc to a point where the horizontal line will lie parallel to the length of the filament and precisely midway between the upper and lower edges of this filament. After the objective lens and cross line disc are so adjusted they are permanently sealed or fastened in position.

' Some variation eXists between different lamps. For this reason when a lamp is re placed the new lamp and its filament must be positioned fo the projection of maximum light. After the original adjustments have been made and the optical systems have been fastened in position a lamp may be rapidly and easily replaced without d'sassembling the machine or the apparatus therein. The new lamp is placed in its holder and adjusted until a sharp image of the filament is projectreproducing sounds.

with the filament ed upon the cross line disc the fixed lines of image precisely bisected by the disc.

" The cross line disc or screen thus acts as an indicator at all times to indicate whether the lamp filamentis in proper condition and proper position'for producing the most cient light at a given. area for recording or The invention will be better understood from a description of the illustrated embodiment in which:

Fig. 1 illustrates the portion of a reproducing machine which includes the apparatus of the invention;

Fig. 2 illustrates schematically a sound recording optical system with the apparatus of the invention associated therewith;

Fig. 3 shows schematically a sound repro ducing optical system with the apparatus of the invention associated therewith; and

. Figs. 4c and 5 show the cross line disc in two forms. I

In the illustrated embodiment Fig.1, an objective lens is shown at 1 and the cross line disc at 2 which with its supporting and adjusting members comprise the apparatus of the invention. The reproducing apparatus of Fig. 1 is typical of one sound reproducing machine in general use. A. film is shown at 82 having a sound record thereon. An optical unit 11 is mounted in holder 12. This optical unit may comprise the parts shown in Fig. 3 such as condenser lenses 43 and 44, physical slit 45 and objective lenses 46, 17 and 48. Screws 18, 1a and 27 may be ma- The cross line disc may nipulated when adjustment of the optical unit 11 is required for focusing the light from the lamp filament 28 upon film 32. Lamp 10 is mounted in holder 15. The lamp is clamped in the holder by adjusting screw 16. The lamp holder 15 is fastened to a movable member 18 which is mounted in the carriage 21. The movable member 18 may be adjusted in a vertical position by the manipulation of screw 1?. In this manner the position of the filament 28 of lamp 10 may be placed in .he correct horizontal plane with relation to the optical axis of optical unit 11. The lamp maybe moved in a horizontal plane by the manipulation of screw 20 which slides the carriage 21 in horizontal directions on its base 22. W hen the lamp filament has been correctly positioned, the movable member 18 is locked in position by the manipulation of screw 13 and the carriage 21 is locked in position by the manipulation of screw 23.

According to present practices the lamp filament adjustments of reproducing machines are best effected by using a film such as 32 bearing a constant frequency sound record. v The filament light is projected through the film sound record to a photoelectric cell and a volume indicator is attached to the output of the photoelectriccell amplifier. The adjustments of the lamp in both the and the adjustment of the optical unit 11 are made while the volume indicator is constantly observed for maximum reading.

he objective lens 1 may comprise two lenses &0 and 4.1 as shown in Fig. 0. These lenses are placed in the cylindrical mounting as shown; A bracket for holding the objective lens unit 1 is shown at 3. This bracket is provided with screw t which may be loosened for axial movement of optical unit 1. When the filament 28 of lamp 10 has been satisfactorily positioned for projecting light upon the film 12 the objective lens unit 1 is adjusted. Unit 1 is moved until a sharply defined image of the filament 28 is projected upon the cross line disc 2. The objective lens 1 is then fastened in position by the manipulation of screw l. It is now necessary to adjust the position of the cross line disc. The mounting 5 of the cross line disc may be arranged with closely fitting slots at thepoints engaged by screws 6 and 7. The cross line disc is now moved vertically until the horizontal line on the disc exactly intersects the sharply defined image of the filament. Screws 6 and 7 are then manipulated to fasten the mounting 5 and consequently the cross line disc 2 permanently in position.

WVith the foregoing adjustments accomplished the character of the lamp filament may at any time be observed.- Eor the best lighting efficiency the lamp filament cannot deviate very much from its original state. A lamp filament either of the ribbon or coil horizontal and vertical directions light valve ribbons 64.

f on which the type mayvery often warp or sag. This occurs from various causes. nary equipment this cannot be readily observed. Ineificient recording or reproduction is ordinarily the first indication to the operator that the lamp filament has deteriorated in some manner. By the use of this lamp'filament indicator, the replacement of a lamp is made compara tively simple. A new lamp may be inserted in the holder 15 and clamped in position with screw 16. Following this the movable member 18 and the carriage 21 maybe manipulated until the horizontal line of the cross line disc 2 intersects the image of the filament projected on the cross line disc 2. The movable member 18 and the carriage 21 are then clamped in position and no further adjust ments are necessary. The cross line disc indicates that the filament of the new lamp is positioned the same as was the filament of the original lamp. This is all that is required to insure maximum efiiciency of lighting.

In the schematic showing of a recording system Fig. 2, the lamp filament is shown in perspective at 42. A condenser lens unit is shown at which comprises lenses 61 and 62. A light valve is shown at 63 with its This light valve may e of the character disclosed by E. C. Wente inUnited States Patents 1,686,355 and 1,638,- 555. An objective lens system is shown at 65 comprising"lenses 66, 67 and 68. A film sound is recorded 69. The lamp and its filament are adjusted in a recording machine in substantially the same manner as hereinbefore described for a reproducing machine. In practice the The condenser lens unit may be adjusted in a similar manner to that described for the optical unit of the reproducing machine. The adjustment of the lamp requires that the image of its filament formed by the condenser lenses shall completely and uniformly illuminate the narrow aperture formed by the light valve ribbons. The condenser lens unit is adjusted so that the image of the filament is focused upon and symmetrically placed with respect to a small rectangular aperture located in the front face of the perpendicular Xed pole piece of the light valve. A line passed through the center aperture corresponds precisely with a line bisecting the aperture formed by the light valve ribbons. Upon the completion of the adjustment of the lamp filament and denser lens unit, justed to sharply focus an image of the lamp filament upon the disc 2 as hereinbefore described for the reproducing system. The cross line disc is then adjusted until the hori- With the ordi is shown at of this pole piece producing systems.

zontal line 9 precisely bisects the filament image as shown at 50. 1 I

,lVhen the foregoing adjustments, for'prO- ducing the most efiicient light in a particular recording machine,- have once been made it is only necessary thereafter to adjustthe lamp at such time or thelamp is replaced. Theuse of the apparatus according to this inventionmakes it unnecessary to disassemble the light valve or readjust the condenser lens The optical system for a reproducing machine shown in F ig. 3 was partly described in connection with the reproducing machine shown in Figil. The projecting a light from the lamp filament 42 to the film and photoelectric cell 49, is shown at 11. In this schematic illustration the lamp filament 42 is shown in perspective.

The physical slitshown at 45 maybe such that complete image of the lamp filament is not projected to the objective lenses 46, i7 and 4.8. 'Thesc-objective lenses project a real image of the slit to the film 32 and photoelectric cell 49. complete image of the lamp filament is however apparent at one side of the slit. Only one type ot-physical slitis illustrated. in Fig. T his slit may however in some cases be adjacent to the film. Res gardless of theloca'tion oi thisslit it is usually desirable tudinal section of the filament. This area of the filament offers the niaxilnun'i brillianey,

with a minimum variation 01" brilliancyand consequently provides illuminationof maximum eificiency. r

land 5 illustrate the cross line disc in two forms. This disc may be made of glass with afiiiely ground surface and'may have only a, lIOIIIZODtZIl and-a vertical line etched thereon shown in F 1g. 4:. For some forms of light filaments this however may not be sufiicient. Occasionall it may therefore be found an advantage to provide a series of finer lines in both horizontal andvertical di rections for accurately positioning the filament'image on the disc or indicator. This type of disc is shown in Fig. 5.

In some instances it may be adjust the disc mounting rection in addition to the in the vertical direction. It is within the scope of this invention to provide this form of adjustment for the. disc. Other adjust ments may also be necessary, as for example, an azimuth adjustment of the horizontal cross line.

The most appropriate and logical tion for the screen or cross line disc and associated objective lens is on the side of the lamp filament opposite to the film an d optical system ordinarily used in recording and re- The disc and its objective lens have been shown in this manner in the illustrated embodiment. The disc and desirable to in a horizontal diadjustment shown posioptical system, for

to, utilize only a narrow longiits objective lens may however be set at any convenient angle fromwhich an image of the lamp filament may be obtained. The arrangement disclosed could be modified to the extent of placing a reflector at any point where an image of the lamp filament exists. A reflected image may then be placed in registry with a reference disc located at a convenient place. It therefore should be con sidered that many modifications can be made and that the disclosure only illustrates one method of applying the invention to sound recording or reproducing machines.

, Vhat is claimed is:

1. In a sound recording or reproducing machine, a lamp having an incandescent filament, means to produce an image of said filament at a particular area, a screen adjustably secured to said machine, means said screen a reproduction of the filament image as it appears at said area, indicating means on said screen, and means to adjust said screen to a point where said entire filament image is placed in a particular relation to said indicating means.

2. In a sound recording or reproducing machine, a lamp having an incandescent filament, an optical system, means to adjust the position of said lamp to bring its filament into alignment with the optical axis of said optical system, means to adjust said optical system to produce a sharp image of said filament at a particular area, a secondary optical system, a screen with markings thereon, means to adjust said secondary optical system to produce a sharp image of said entire filament on said screen, and means to position said screen to so relate the image and markings thereon as to produce an indicator to indicate the correctly adjusted position of said lamp filament.

In a sound recording or reproducing machine, a lamp having an incandescent filament, an optical system, position of said lamp to bring said filament into alignment with the optical axis of said optical system, means to adjust said optical system to produce a sharp image of said filament at a particular area, asecondary optical system, a screen with'marlrings thereon adjustably fixed to said machine, means to adjust said secondary optical system to produce a sharp image of said entirefilament on said screen, and means to position said screen to produce on filament upon said means to adjust theto 50- relate the image and markings thereon as to produce an indicator to indicate the correctly adjusted position of said lamp filament. i V

4. A sound recording or reproducing ma chine having a light source and means for focusing said light source on a particular area for sound translation comprising a lamp with an incandescent filament, an optical unit, adjusting means for positioning said lamp filament, and adjusting means for said optical unit for focusing the light'from said filament upon said particular area, a second optical unit for said machine adjustably mounted therein approximately in' alignment with said first optical unit, a screen with crossmarkings thereon adjustably mounted in said machine in alignment with said optical units, means for adjusting and fixing said second optical unit for focusing a sharply defined image of said adjusted lamp filament upon the screen, and means for adjusting and xing the screento have the cross-markings intersect the image of the lamp filament to be a permanently fixed indicator ofthe positional adjustment required for the filament of any lamp placed in said machine so as to be in accord with the adjustment of said first optical unit.

5. A sound recording or reproducing machine having a light source and means for focusing said light source on a particular area for sound translation comprising a lamp with an incandescent filament, an optical unit, adjusting means for positioning said lamp filament-and adjusting means for said optical unit for focusing the light from said particular area, a second optical unit for said machine adjustably mounted therein approximately in alignment with, said first optical unit, a screen with cross-markings thereon adjustably mounted in said machine in alignment with said optical units, means for adjusting and fixing said second optical unit for focusing a sharply defined image of the lamp filament strands upon a screen, and means for adjusting and fixing the screen to have the cross-markings intersect the image of the lamp filament strands as a permanent indicator of the positional relation said filament strands shall bear to said markings for indicating the characters of said filament.

' WILLIAM HERRIOTT. 

